Problem: Balance the following chemical equation: $ $ $\text{CH}_4 +$ $\text{Cl}_2 \rightarrow$ $\text{CCl}_4 +$ $\text{HCl}$
Solution: $\text{C}$ is already balanced. There are $4 \text{ H}$ on the left and only $1$ on the right, so multiply $\text{HCl}$ by ${4}$ $ \text{CH}_4 + \text{Cl}_2 \rightarrow \text{CCl}_4 + {4}\text{HCl} $ That gives us $8 \text{ Cl}$ on the right and only $2$ on the left, so multiply $\text{Cl}_2$ by ${4}$ $ \text{CH}_4 + {4}\text{Cl}_2 \rightarrow \text{CCl}_4 + 4\text{HCl} $ The balanced equation is: $ \text{CH}_4 + 4\text{Cl}_2 \rightarrow \text{CCl}_4 + 4\text{HCl} $